Cycle syncing, also known as menstrual cycle syncing or menstrual cycle awareness, is the practice of aligning various aspects of one's life, including diet, exercise and work, with the different phases of the menstrual cycle. The menstrual cycle typically consists of four phases: menstrual, follicular, ovulatory and luteal. Each phase is associated with hormonal changes in the body, and proponents of cycle syncing believe that adapting activities to these hormonal fluctuations can optimize health and well-being.

Cycle syncing has become a popular topic on social media, as some claim that it is the key to adaptation for female physiology. The research, however, is far from clear. As a health and exercise professional, you should be aware of this hot topic and understand how the menstrual cycle may impact training, but it is essential to acknowledge that the research does not support completely changing workouts based on phase of the menstrual cycle.   

The Basic Concept of Cycle Syncing

The concept of cycle syncing was introduced by functional nutritionist Alisa Vitti in her 2014 book, WomanCode, and focuses on adjusting workouts and nutrition to match hormone fluctuations during phases of the menstrual cycle. Vitti asserts that research ignores women and female sex hormones, and, while there is a significant need for more female-focused research in exercise physiology, the approach largely ignores the research that does exist. 

The tenets of cycle syncing suggest performing high-intensity interval training (HIIT) and cardio exercise during the luteal and ovulatory phases and focusing on lower-intensity cardio and strength or body-weight workouts during the follicular and menstrual phases.

Understanding the Menstrual Cycle 

The menstrual cycle (MC) is often referred to as a 28-day cycle, but in reality, a normal cycle can range from 21 to 35 days. The MC is driven by hormones in the brain and ovaries, with the rise and fall of hormones triggering different phases.

The menstrual cycle tends to stabilize and be more predictable during a person’s twenties but can become less regular due to life changes such as pregnancy and lactation. Stress has also been shown to cause hormone fluctuations. Irregular periods can also be caused by polycystic ovary syndrome (PCOS), very low body weight and thyroid disorders. Menstruation typically becomes more irregular approaching menopause as well.

The Phases of the Menstrual Cycle 

Menstrual Phase: The shedding of the uterine lining typically occurs for three to seven days if pregnancy has not taken place. For those who have a 28-day cycle, this phase lasts for days one through five. 

Follicular Phase: During the follicular phase, estrogen increases, which leads to the thickening of the uterine lining. Follicle stimulating hormone (FSH) also increases and causes follicles in the ovaries to grow. During a 28-day cycle, the follicular phase usually takes place from days six through 14. During days 10 to 14, a fully mature egg is produced from one of the developing follicles. 

Ovulatory Phase: Ovulation typically takes place at day 14 in a 28-day cycle. An increase in luteinizing hormone (LH) causes the ovary to release an egg, which is considered ovulation.

Luteal Phase: The luteal phase lasts from about days 15 to 28. During this time, the egg leaves the ovary and travels through the fallopian tubes to the uterus. Progesterone rises to prepare the body for pregnancy. If the egg is fertilized, it will implant in the uterine wall. If it does not become fertilized, estrogen and progesterone levels drop and the lining will shed during menstruation. Cycle syncing recommends reducing strength training during the luteal phase, which, as mentioned above, is half of the month. 

What Does the Research Say About Cycle Syncing?

Researchers who conducted a 2020 meta-analysis of 78 studies concluded that “exercise performance might be trivially reduced during the early follicular phase of the MC, compared to all other phases.” The study specifically mentioned that current data on the topic of hormones during the MC and exercise performance are conflicting, and there is no consensus on whether exercise performance is affected by the phases of the menstrual cycle. Therefore, there is no need for sweeping generalities or recommendations for all people with a menstrual cycle. 

While the meta-analysis showed little to no physical reasons for adapting training to one’s cycle, what about the mental or emotional impact of the menstrual cycle? After all, many experience a range of symptoms at different times during their cycle, particularly immediately before and during the menstrual phase (see sidebar). Could those symptoms impact exercise performance? A 2022 study on the relationship between strength and hormone levels found the greatest strength fluctuations were, in fact, tied to mental state (self-reported motivation, perception of own physical performance level, pleasure level and arousal level). However, the researchers stated that “no direct correlation was observed between the variations in sex hormones and physical performance parameters.”

It’s important to note that cycle syncing recommendations largely run contrary to current exercise recommendations for adults. Current exercise guidelines recommend performing two or more days of muscle-strengthening activity and at least 150 minutes of moderate-intensity aerobic activity each week. Reducing strength training for nearly half the month (luteal phase) is counterproductive in terms of gaining or preserving muscle mass, and it would be irresponsible for health and exercise professionals to recommend this approach to their clients.

“While changes in nutritional needs, energy, strength and performance are real, they’re often small effects, non-meaningful effects, or come down so much to individual experience [that] at this time we cannot say there are any absolutes,” says Dr. Alyssa Olenick, who studies metabolism and the relationship between hormones and exercise. “Additionally, every cycle, both month to month and between individuals, is different.”

Dr. Olenick suggests that a few common habits could make it difficult for some to know if their workouts are suffering due to their cycle or are caused by a lack of energy. She has observed that some people tend to “undereat compared to their exercise needs, don’t follow good exercise training programs, work out for only calorie burn or are often underloaded.” Addressing these habits could more positively impact both performance and overall health than simply avoiding certain types of exercise during different phases of the menstrual cycle.

For these reasons, adjustments to a training program should be made on a case-by-case basis, depending on the symptoms experienced during any given MC. The most effective approach to managing these symptoms is to focus on nutrition, stress management and sleep, rather than follow broad generalizations for all menstruating individuals. 

How to Support Clients During Their Menstrual Cycle

As previously stated, advising menstruating individuals to decrease their load for nearly two weeks of the month is not only a bad idea, particularly given how quickly fitness gains can be lost, but it also goes against current exercise recommendations and rejects current studies that have examined the relationship between female hormones and exercise. 

Rather than completely altering a client’s training schedule based on the phase of the menstrual cycle, you can support your clients by urging them to take note of current symptoms and focus on consuming high-quality foods and getting adequate sleep.  

Noting common effects experienced during the menstrual cycle can make it easier to anticipate symptoms and plan ahead. For example, it’s common for energy levels to fluctuate, along with levels of hunger and pain or discomfort. Taking these symptoms into account and planning workouts around expected symptoms can make it possible for clients to optimize high-energy days and to rest when experiencing discomfort or fatigue. 

As Dr. Olenick mentioned, symptoms vary between individuals, so it can be helpful to ask clients to share if they have or are experiencing symptoms severe enough to affect their training program. For example, if a client typically experiences significant cramps or excessive bleeding on the first day of the menstrual phase, they may not welcome an intense abdominal workout. And while some might want to exercise intensely during this phase, others may prefer yoga or long, lower-intensity cardio training. As with all training, there is no single approach that works for everyone.

Here are some ideas for how you can support clients who are experiencing symptoms or side effects due to menstruation: 

• Adjust exercise intensity and duration by swapping a higher-intensity day with a rest day or a lower-intensity workout when a client’s symptoms are most severe.
• Urge clients to prioritize high-quality sleep, particularly when energy levels feel particularly low.
• Address pain by utilizing over-the-counter medications like ibuprofen or heating pads for pelvic or back discomfort. However, those whose lives are significantly disrupted by menstrual pain or bleeding should consult with their healthcare provider.

Keep the Conversation Going

While research suggests that it is not necessary to completely change one’s workouts based on the menstrual cycle, the discussion around cycle syncing has allowed people experiencing menstruation to be more in tune with their bodies and to better understand the phases of menstruation. As a health and exercise professional, having a general understanding of the menstrual cycle and common symptoms your clients may experience can serve to make them feel more supported and, as a result, achieve better outcomes from their training.  

There is no downside to tracking one’s cycle and getting more in tune with one’s body. By tracking and anticipating common symptoms or side effects, clients can plan for when they may experience changes in energy levels or mood, and, if necessary, implement pain-management strategies. 

Encourage your clients to make any needed adjustments to their training programs by listening to their bodies. If they are experiencing pain or fatigue, for example, modifications can be made or workouts and rest days can be switched. However, there is no evidence to support the need to drastically reduce or change physical-activity patterns during any phase of the menstrual cycle.  

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